1. Field of the Invention
The present invention relates to an apparatus for the manufacture of a hose. More particularly, the present invention relates to an apparatus for the manufacture of a hose wherein a specific clogging liquid applicator is used at the initial stage of the coating treatment for a tubular textile jacket.
2. The Description of the Prior Art
Heretofore, it is widely known as a process for the manufacture of a hose that a coating of rubber or a synthetic resin is formed on the external surface of a tubular textile jacket usually made of fibers woven or knitted in a tubular form, and the resultant coated jacket is then evaginated. For example, the methods disclosed in British Pat. No. 957,927 and U.S. Pat. Nos. 3,437,537, 4,032,677 and 4,020,790 belong to a process of this type. In these conventional methods, a coating of rubber or a synthetic resin is formed on the external surface of a tubular textile jacket usually by passing the jacket through one or more baths of a coating liquid such as a latex or a solution of rubber or a synthetic resin and then the coating liquid attached to the external surface of the jacket is solidified.
The coating liquid usually used in the above mentioned prior art methods is of a relatively low viscosity, generally below 200 cp. Thus, the jacket is passed through a bath of a coating liquid having such a low viscosity whereby excess coating liquid attached to the external surface of the jacket is allowed to flow down freely before solidification to form a very thin coating on the surface of the jacket. This coating treatment is repeated several times to form a beautiful and smooth coating having an even, given thickness on the surface of the jacket without permitting the formation of undesirable pinholes and like imperfections in the coating.
However, a coating liquid of such a low viscosity is so high in penetrating force that it permeates to the internal surface of the jacket through the retiform texture. The internal surface of the jacket is, therefore, soiled, and, when the jacket is evaginated, the external surface of the resultant hose will be dirty with the penetrated latex or resin. As a means for preventing such defects in the final product, the pervious reticulate structure of the jacket is initially clogged with a clogging liquid to prevent permeation of the coating liquid through the retiform texture of the jacket. The most convenient method for clogging the pervious reticulate structure of the jacket comprises passing the jacket through a highly viscous clogging liquid such as a highly concentrated latex, a solution or a plastisol of rubbber or a synthetic resin or a molten liquid thereof, prior to the coating treatment with the coating liquid, and then squeezing the jacket for rubbing a part of the clogging liquid attached to the surface of the jacket into the interstices or voids in the retiform texture of the jacket and removing the remaining larger part of the clogging liquid. A clogging liquid with a viscosity between 1,000 cp. and 20,000 cp, inclusive, can effectively clog the interstices or voids in the reticulate structure of the jacket without penetrating therethrough.
A difficult problem arises in this case. Because of the tubular structure of the jacket, it is difficult to rub the clogging liquid into the interstices or voids evenly over the entire surface of the jacket. When the clogging liquid is wiped away from the surface of the jacket in flattened state with rollers or a doctor knife, the clogging liquid in the folded edge areas of the jacket cannot be removed and a unnecessarily large amount of the clogging liquid remains in these areas. Even if a special device is used to scrape off the clogging liquid from the folded edge areas, it is difficult to provide clogging of the interstices or voids evenly over the entire surface of the jacket.
On the other hand, it is possible to remove the clogging liquid by maintaining the jacket which has been passed through a bath of the clogging liquid in an inflated state with an expanding device and then providing a squeezing device in a ring formed around the inflated jacket to squeeze it evenly over the full circumference. According to this method, the jacket is in a uniform state over the full circumference and hence the clogging liquid can be applied evenly into the interstices or voids over the entire surface of the jacket without any problem of irregularity due to folding. This method requires, however, to keep the jacket almost circular in its cross section and to squeeze the external surface of the jacket evenly by a constant force over its entire circumference. Such requirements are difficult to realize in the existing processes actually put into practice because a small fluctuation in diameter of the jacket made by weaving or knitting fibers in a tubular form is unavoidable. In order to continuously operate the coating treatment, it is necessary to supply the jacket without inerruption. As the length of the jacket is limited or, in other words, it is practically impossible to provide a splice-free unlimitedly long tubular textile jacket, a splicing treatment of the jacket is necessary for continuously supplying it to the apparatus. In this case, the jointed portion of the jacket becomes harder and is increased locally in diameter. Thus, it is essential that the expanding device and the squeezing device have good compliance with fluctuations in the diameter of the jacket. In case a rigid mandrel as disclosed in U.S. Pat. No. 3,437,537 and a metal ring are used as an expanding device and a squeezing device, respectively, for applying a clogging liquid onto the surface of the jacket, these devices will not satisfactorily comply with fluctuation in the diameter of the jacket as seen in a spliced portion thereof. Consequently, even a slight change in diameter of the jacket makes squeezing uneven and, in the extreme case, the spliced portion of the running jacket cannot pass through a slit between the mandrel and the metal ring. In case an endless double-tubing as disclosed in U.S. Pat. No. 4,032,677 is used as an expanding device for the jacket in the treatment for applying thereto a clogging liquid, such double-tubing will inflate the jacket well, even if the diameter of the jacket changes to some extent but will dent when squeezed with a ring-shaped squeezing device to remove excess clogging liquid from the jacket. Thus, a good expanding device for the jacket in the treatment for applying thereto a coating liquid is not always suitable as an expanding device in the application of a clogging liquid to the hose jacket. In the above mentioned situation, there is a great demand for developing a new expanding device suitable for use in a treatment of the jacket with a clogging liquid.